Roll forging machine

ABSTRACT

A forging machine comprising at least two roll carriers arranged on opposite sides of material to be reduced. Each roll carrier includes a bush having one or more arms attached thereto. Work rolls are arranged in the ends of the arms. The roll carriers are moved in noncircular paths, the paths being somewhat flattened when engaging the material to be reduced. The machine also includes means for altering the distance between the work rolls in the flattened portion of their paths.

United States Patent Inventor Appl. No.

Filed Patented Assignee Priority Rolf Franke Osterath, Germany Dec. 18, 1968 May 4, 1971 Brightside Foundry 8: Engineering Company Limited Sheffield, Yorkshire, England Dec. 18, 1967, Aug. 17, 1968 Great Britain 57417/67 and 39456/68 ROLL FORGING MACHINE 12 Claims, 19 Drawing Figs.

US. Cl.....

Int. Cl

B211) 13/20 Field of Search [56] References Cited UNITED STATES PATENTS 771,611 10/1904 Davis 72/190 802,048 10/1905 Lambert et al. 72/ 190 1. ,024,485 4/1912 Nowak 72/190 3,114,276 12/1963 Uebing et al.... 72/184 3,436,944 4/1969 Lombard 72/215 3,439,519 4/1969 Gerding 72/189 Primary Examiner-Lowell A. Larson Attorney Holcombe, Wetherill and Brisebois ABSTRACT: A forging machine comprising at least two roll carriers arranged on opposite sides of material to be reduced. Each roll carrier includes a bush having one or more arms attached thereto. Work rolls are arranged in the ends of the arms. The roll carriers are moved in noncircular paths, the paths being somewhat flattened when engaging the material to be reduced. The machine also includes means for altering the distance between the work rolls in the flattened portion of their paths.

Patented May .4, 1911 7 3,577,760

' 14 Sheets-Sheet 1 Patented May 4,1971 3,577,760

.14 shuts-sheet 2 Pmmd 7 May 4, 1971 14 Sh'ee ts-Sheet 3 FIG. 4.

Patented May 4, 1971 14. sheets sheat 4 RV mv Patented May 4,1971 13,517,760

14 Sheets-Sheet 5 FIG. 5A.

Patent ecl May 4, 1971 14. Sheets-Sheet 6 Patented .May 4,1971 3,577,760

14 She ets-Sheet 7 Patented May 4; 1 971 I 3,577,760

14 Sheets-Sheet 8 M CURVE B 125 155 155' 215 245 275 305 ggg. 50 270 240- FIG. 8A.

Patented May 4, 1971 l II 14- Sheets-Sheet 1 O Patented May 4, 1911 5 3,577,760

14 Sheets- 8110 11 66 65 2762 22 FIG. 9A.

Patented May 4, 1971 14 Sheets-Sheet 12 Patented May 4, 1971 3,577,760

14 Sheets-Sheet 13 FIG. //A.

ROLL ronomc MACHINE The present invention relates to a roll forging machine.

According to a first aspect of the invention there is provided a roll forging machine including a frame, at least two roll carriers mounted in the frame for movement about displaced axes, and means for moving said roll carriers so that rolls mounted in said carriers move in noncircular paths.

According to a second aspect of the invention there is provided a roll forging machine including a frame, at least two roll carriers mounted in the frame with their axes displaced relative to each other and means for rotating said roll carriers in synchronism so that rolls mounted in the carriers move in noncircular paths, said paths being somewhat flattened in an operative zone, that is a zone of closest proximity of the roll carriers.

Preferably the roll carriers are arranged in oppositely disposed pairs for rotation about parallel axes in directions v counter to each other.

Each roll carrier may comprise a bush having at least one radially extending ann attached thereto. When there are two or more arms attached to'the bush they are spaced equally around a common axis. At least one roller is provided in the free end of each arm so that the axis of the roller is arranged parallel to said common axis.

Each roll carrier may be rotated in a planetary manner about its common axis. ln which case the planetary rotation of each roll carrier may be enabled by an internal ring gear secured to the frame of the machine; in the ring gear having teeth provided around the inner circumference thereof, and a pinion which is rolled around the ring gear by an eccentric fonned on a drive shaft, the ring gear being concentric with the axis of the drive shaft. The pinion if fixed to a sleeve which is rotatable about the eccentric but is fixed with respect to the associated roll carrier. The numbers of teeth on the ring gear and the planet pinion are chosen so that having regard to the number of rolls in each roll carrier, the rolls follow each other in exactly the same noncircular path.

In the case of a roll carrier with five rolls, the ring gear may have for example 66 teeth whilst the pinion has 55 teeth. By this arrangement the locus of any one roll approximates to a regular hexagon having substantially straight sides but with rounded corners. The hexagon-shaped locus is obtained as follows:

With the ratio of 6:5 between the number of teeth on the ring gear and the number of teeth on the pinion and starting at one of the six comers of the hexagon then, after the drive shaft with the eccentric has made five-sixths revolution, the roll carrier has made one-sixth revolution in opposite direction and has formed the next comer, thus having turned through an are of The line of motion of the rolls is modified by the rotation of the eccentric so that instead of sweeping out a circular path, the eccentric superimposes a sinusoidal motion on the rolls whereby for every five revolutions of the drive shaft the rollers can be arranged to effectively follow a path which resembles a hexagon having substantially straight sides but with rounded comers. In use the'motion of the rolls engaging the material on opposite sides is arranged so that they follow substantially straight converging paths until the distance between them corresponds to the finished size of the product after which they break away or diverge along curved paths, the latter corresponding to the rounded corners of the hexagon-shaped loci.

If desired adjustment means may be operatively coupled to at least one roll carrier of each pair of altering the path of the or each roll carrier inthe zone of closest proximity of opposed roll carriers thereby altering the distance between the opposed roll pairs.

ln one arrangement the adjustment means may comprise a lever attached to the ring gear of each roll carrier whereby by rotating the ring gear relative to the pinion, whilst holding the drive shaft stationary, the somewhat flattened paths of the opposed roll pairs in said operative zone are caused to converge to a greater or lesser degree than previously depending on the direction of rotation of the ring gear.

Alternatively, the adjustment means may act on the drive shafts to cause the pairs of roll carriers to be moved bodily towards or away from each other. Said adjustment means may comprise wedges, screwdowns or two pairs of eccentric sleeves. In the last case, the sleeves of each pair are fitted one into the other. The ring gear is positioned in the inner eccentric sleeve of one pair and is prevented from turning by a lever attached to the frame and the bearing race supporting the end of the drive shaft remote from the ring gear is positioned in the inner eccentric sleeve of the other pair. Means are coupled to each sleeve so that by symmetrically turning the respective pairs of sleeves there is a straight line shifting of the particular roll carrier towards or away from the material to by rolled,,

Another form of the adjustment means may include means to bodily move each roll carrier whilst simultaneously rotating the ring gear. Such means may comprise two eccentric sleeves. The ring gear is positioned in one eccentric sleeve and is attached to one end of a lever, the other end of which is held in a pivotally movable member, and the bearing race supporting the end of the drive shaft remote from the ring gear is positioned in the other eccentric sleeve. By symmetrically turning the sleeves there is a shifting of the particular roll carrier towards or away from the material to be rolled as well as a relative movement between said one eccentric sleeve and the ring gear due to a pivoting movement of the lever about the pivoted pocket.

In order that the invention may be fully understood and readily carried into effect, embodiments thereof will not be described, by way of example only, with reference to the accomp'anying drawings, in which:

FIGS. 1 and 2 are diagrammatic illustrations of a machine embodying the invention,

FIG. 3 is a general transverse cross-sectional view, in a plane corresponding to that indicated 3-3 in FIG. 2, through a constructional embodiment having two pairs of opposed roll carriers,

FIG. 4 shows the complete roll path of a roll of the roll forging machine to be described with reference to FIG. 3,

FIG. 5 represents a general cross section through a roll forging machine having rotary adjustment of the internal ring gear,

FIG. 5A is an enlarged view of a portion of FlG. 5,

FIG. 6 represents a front view of the adjustment means for rotating the ring gear,

FIG. 7A is a diagram of a roll carrier showing the relative positions of the rolls with the ring gear in the normal position,

FIG. 7B is a diagram of a roll carrier showing the relative positions of the rolls after the ring gear has been rotated through 4,

FIG. 7C is a similar diagram to FIG. 7B in which the roll in operation has been turned clockwise to bring it vertical, the angle at the crank centers having been increased from 10 as shown in FlGS. 7A and 78 to 35,

FIGS. 8A and 8B show curves A to F which illustrate the effect of rotating the ring gear by up to 4,curve A corresponds to a nonadjusted position whilst curve F shows the 4 position,

FIG. 9 represents a general cross section through a roll forging machine having means to adjust the roll carrier of each pair bodily towards and away from the material being rolled,

FIG. 9A is an enlarged view of a portion of FIG. 9,

FIG. 10 is a front view of the adjustment means for adjusting the roll carriers towards and away from the material being rolled,

FIG. 11 represents a general cross section through a roll forging machine having means to adjust the roll carriers towards and away from the material being rolled both by circular displacement and by rotating of the ring gear,

FlG. 11A is an enlarged view of a portion of FIG. 11,

FIG. 12 is a front view of the adjustment means shown in FIG. 7, and

HQ 13 shows two roll curves obtained by using the adjustment means shown in FIGS. 7 and 8.

Referring now to FIG. I, the machine includes a pair of oppositely disposed roll carriers 110, I10 mounted for contrarotation in a common plane about parallel axes 112, 112.

opposed roll pairs become operative in turn to reduce the thickness of a length of rolling mill produce being fed relatively slowly between them, that is to say at a rate somewhat slower than the rate of travel of the rolls through a so-called operative zone z which extends from a plane in which the rolls first contact the length of product to just beyond a plane containing both axes 1 12.

The roll carriers 110 are mounted for movement towards and away from each other (as indicated by the arrows) in phased relation to their rotation whereby the rolls mounted in said carriers move in paths which are not truly circular but are somewhat flattened in the operative zone z as shown by the chain dotted lines f in FIG. 1. There is thus produced an improved rolling action, much better than would be produced if the rolls were to move in truly circular paths such as indicated by the chain dotted lines I in F IG. 1.

InFIG. 2, preferred means for moving the carriers towards and away from each other in phased relation to their rotation are illustrated diagrammatically. Said means include respective eccentric mechanisms whereby the axes 112, 112 are carried around respective drive shafts 116, 116 to move the carriers towards and away from each other respective planetary gear sets associated with said eccentric mechanisms for imparting rotation to said carriers. The planetary gear set associated with each eccentric mechanism includes a fixed annulus 118, concentric with the axis 116, and a planet pinion 120, fixed with respect to the respective roll carrier, which rolls around inside the annulus as the eccentric on which the carrier is mounted rotates. The numbers of teeth of the annulus and planet pinion are of course chosen so that, having regard to the number of rolls mounted in each roll carrier, said rolls follow each other in exactly the same noncircular path, but this will be within the scope of a skilled designer to achieve.

In the following description of FIGS. 3 to 13 similar reference numerals will be used to identify corresponding parts of the machine. Further, as the roll carriers 12 are identical to each other only one roll carrier 12 will be described in detail and similar reference numerals will be used to identify corresponding parts of the other roll carriers 12.

Referring more particularly to FIG. 3, the roll forging machine comprises a frame 11 in which is mounted two pairs of oppositely disposed roll carriers 12. The roll carriers '12 of each pair are mounted parallel to each and at right angles to the roll carriers of the other pair. Each roll carrier 12 comprises a bush 14 having a plurality of arms 30, e.g. five arms, nonrotatably secured thereon. The arms 30 are spaced equally around the bush l4 and extend radially therefrom. A roll 31 is provided in the end of each arm 30 and is arranged with its axis parallel to the axis of the bush 14.

Each roll carrier 12 is rotatably mounted on an eccentric 24 formed on a drive shaft 20 which is supported in the frame 11 by means of thrust bearings 21 and bearing races 22 so as to rotate about its axis 23. The axis of the eccentric 24 is denoted by the reference 25.

A planetary gear set comprising an internal ring gear 26 and a planet pinion 27 is associated with the roll carrier 12. The ring gear 26 is mounted in the frame 11 so as to be concentric with the drive shaft 20 and the planet pinion 27 is secured to a sleeve 28 which is rotatable about the eccentric 24 and which is nonrotatably secured to the bush 14.

The drive for the respective roll carriers 12 is derived from a common source(not shown) which is coupled to two shafts 46, 47. The shafts 46, 47 are coupled respectively to the drive shafts 20 of one of the pairs of roll carriers 12, in the drawings these are the top and bottom roll carriers 12. The respective drive shafts 20 of said one pair of roll carriers 12 are coupled through bevel gears 48 to respective drive shafts of the other pair of roll carriers 12 as shown in FIG. 3, i.e. the top roll carrier 12 is coupled to the left-hand roll carrier 12, whilst the bottom roll carrier 12 is coupled to the right-hand roll carrier 12. The roll forging machine 10 is operated so that each pair of oppositely disposed roll carriers 12 are rotated in synchronism. Also the pairs of roll carriers become operative in turn so that a length of material being slowly drawn drawn or pushed through the machine is alternately acted on by the pairs of roll carriers 12 in the mutually perpendicular planes.

If a roll carrier 12 equipped for example with five rolls 31 and with 66 teeth on the internal gear 26 and 55. teeth on the pinion 27 is operated by rotating the drive shaft 20, which causes the center of the pinion 27, that is the axis 25, to be moved at the angular speed of the drive shaft 20 on an orbit round the drive shaft axis 23 and at the same time the rate of precession of the pinion 27 is one-fifth of a revolution for each revolution of the drive shaft 20. In so doing the arms of the roll carrier are angularly displaced through an arc of 72 relative to the axis 25 of the roll carrier in a direction opposite to that of the direction of the drive shaft 20 and also the axis 25 is itself turned through a circle of radius x. Accordingly the motion of the rolls is a noncircular one in that the eccentricity of the eccentric 24, i.e. the distance x (FIG. 1) between the axes 23 and 25, modifies the line of motion of the rollers 31 by superimposing a sinusoidal curve on a 60 arcuate circular line of motion. By having a relatively small eccentricity and with the rolls 31 at a relatively great distance from the axis 25, e.g. in a ratio of say I to 25, then the locus of any one roller 31 approximates to that of a regular hexagon having substantially straight sides and curved corners, for example, see FIG. 4.

The finished size of the material being rolled can be determined by choosing a suitable crank angle a i.e. the angle between the centerline 50 (FIG. 4) passing through the axes 23 of the drive shafts of the opposed roll carriers of a respective pair and the line passing through the axes 23 and 25 when the arm 30 of the roll 31 in operation is parallel to the centerline 50. If the ring gear 26 is rotated relative to the pinion 27 then the crank angle is changed thereby increasing or decreasing the minimum separation of the rolls 31 of opposed roll carriers and adjusting the size of the finished product accordingly.

One means of rotating the ring gear 26 relative to the pinion 27 is shown in FIGS. 5 and 6.

In the embodiment of FIGS. 5, 5A and 6 the ring gear 26 is mounted on a sleeve 15 so as to be concentric with the drive shaft 20. The sleeve 15 is mounted rotationally in an outer sleeve 16 in the frame 11. The lower end of the sleeve 15 remote from the ring gear 26 is secured to a cover 32- by means of keys 17. The cover 32 together with the ring gear 26 are rotatably about the axis 23 by an adjustment means to be described.

The cover 32 is formed as a lever. In the end of the cover remote from the ring gear 26 is a U-shaped cutout 33 is provided. The cutout 33 is arranged symmetrically about a line 34 passing through the axis 23 of the drive shaft 20. A sliding block 35 is provided in the cutout 33. A crank 36 is provided which is located in an aperture 37 in the sliding block 35. The crank 36 is eccentrically mounted in the frame 11 of the roll forging machine 10. A lever 38 is secured to the crank 36. The lever 38 serves to turn the crank 36 which in turn rotates the cover 32 and the ring gear 26 relative to the eccentric 24 which is held stationary by the bevel gears 48. The lever 38 is turned by a nut 40 and screw 39 mechanism which is actuated by a drive means, for example, a gear motor 41. Preferably the gear motor 41 is arranged to drive the screws 39 of all four roll carriers.

In FIG. 7A is shown an example in which the crank angle a is 10 and in which a reference line A extending from the axis 23 of the drive shaft 10 and representing the angular position of the ring gear 26 is at right-angles to the centerline 50. FIG. 7B shows the effect or rotating the ring gear 26, i.e. the reference line A, through 4 whilst holding the drive shaft 20 stationary and maintaining the crank angle at 10. The roll 31 in operation is also moved through an angle of more than 4 the exact angle being determined by the ratio of the number of teeth on the ring gear 26 to the number of teeth on the pinion 27; for example if the ring gear 26 has 66 teeth and the pinion v 27'has 55 teeth then the angle through which the reference line A moves is six-fifths of 4 which equals 48". HO. 7C shows the position of the roll arm 30 when the drive shaft 20 has been turned to bring the roll arm 30 from the position of H0. 78 to a disposition parallel again to the centerline 50 and illustrates that, by altering the ring gear by 4,the crank angle ahas been increased from l to 35. This increase in crank angle has the effect of increasing the separation of roll 31 form the axis 25 of the ring gear and therefore decreasing the roll bite.

Reference in now made to FIGS. 8A and 8B which show the loci of the roll in operation for various crank angles a. Curve A corresponds to a crank angle of l0,that is, with the rolls in the position shown in FIG. 7A, and curve F corresponds to a crank angle of 35,that is, with the rolls in the position shown in FIG. 7C and with ring gear 26 having been rotated through an angle of 4. Curves B, C, D and E show the loci for crank angles of l, 20, 25 and 30 which are obtained by rotating the ring gear 26 through angles between 0 and 4.

it will be observed that as the crank angle increases the finished size of the material being rolled decreases and also that the loci are rotated anticlockwise in the drawings as the crank angle increases. By rotating the loci anticlockwise the curved part of the loci bite deeper into the material being rolled thereby reducing the finished size thereof.

FIGS. 9, 9A and show an embodiment in which one roll carrier 12 of each pair of roll carriers is bodily adjustable towards or away from the centerline of the material being rolled. lt is within the scope of the present invention to make each roll carrier adjustable in this way.

Referring to FIGS. 9 and 9A, the bottom roll carrier 12 and the right-hand roll carrier '12 are fixed in the frame 11 relative to each other. The drive shafts of these two roll carriers are operatively coupled to each other by the bevel gears 48, the gears 48 are rotated by a common drive means 60 coupled through a main shaft 45 and the shaft 47 to one of the drive shafts 20.

As the means for bodily adjusting the other roll carrier of each pair are identical, only one of them will be referred to in the following description and it is to be understood that the other of them functions in a similar way.

The internal ring gear 26 is secured to a cover 62 which is in the form of a lever and which is prevented from turning by means of the end of the cover 62 remote from the ring gear 26 being secured in a bracket 63 attached to the frame 11 of the roll forging machine 10. The ring gear 26 is positioned in eccentric sleeves 65 and 66 located in the frame 11. Each sleeve 65, 66 is coupled to respective hydraulic cylinders 67, or corresponding electromechanical adjusting equipment, mounted on the frame 11, one arranged on each side of the cover 62, as shown in FIG. 10.

On the opposite side of the roll carrier, a housing 68 in which the bearing race 28 is positioned, is formed as an eccentric sleeve. The housing 68 is enclosed by another eccentric sleeve 69. The housing 68 and the sleeve 69 are coupled to respective hydraulic cylinders 70, or electromechanical adjusting equipment, mounted on the frame 11.

By operating the cylinders 67 together, the eccentric sleeves 65, 66 are turned in opposite directions causing the ring gear 26 and the pinion 27 to be moved in a straight line either towards or away from the center of the roll forging machine 10. A similar movement of the opposite side of the roll carrier is produced by operating the cylinders 70 which turn the housing 68 and the eccentric sleeve 69 in opposite directions.

When an adjustment is to be made to the roll carrier 12, the operation of the cylinders 67 and 70 is synchronized so that the axis 23 of the drive shaft 20 is maintained parallel to the axis of its corresponding fixed roll carrier, as the roll carrier is shifted either towards the center of the roll forging machine 10 thereby causing a reduction in the finished size of the material to be rolled or away from the center therebycausing an increase in the finished size of the material to be rolled. By this arrangement the drive shafts 20 of the respective movable roll carriers 12 can be adjusted independently and also the rolling of rectangular sections is possible. As the drive shafts 20 are adjustable independently it is necessary that they should be driven by independent drive shafts 71, 72 through universal couplings 73, 74 respectively. The drive shafts 71, 74 are coupled by way of the main shaft 45 to the common drive means 60 which rotates the pairs of roll carriers in synchronism.

if desired the bodily adjustment of the roll carriers may be effected by screwdowns or wedges and which are used in place of the eccentric sleeves 65, 66, 68 and 69. I

By the above-described means any of the roll curves shown in FIGS: 8A and 83 can be obtained initially, however as there is no rotation of the ring gears 26 then there is no rotation of the roll curves as the crank angle remains the same. Operation of the adjustment means will cause a parallel shifting of the initial roll curve towards the pass line.

FIGS. 11, 11A and 12 show a means of adjusting the roll carriers 12 which is effectively a combination of the embodiment shown in FIGS. 5, 5A and 6 and of the embodiment shown in FIGS. 9, 9A and 10 since there is produced both a form of a lever. The end of the cover remote from the ring gear is attached to a bracket 83 which is pivotally movable in the frame 11 of the roll forging machine 10. The ring gear 26 is positioned inside an eccentric sleeve 85 which is rotatable in the frame 11 and to which is attached an arcuate-shaped worm gear 86. A worm 87, which is driven by a means not shown, is arranged to mesh with the worm gear 86. On the opposite side of the roll carrier 12, the bearing race 22 is positioned in an eccentric bearing housing 88 which is rotatably mounted in the frame 11. An arcuate worm gear 89 of the same radius of curvature as the worm gear 86 is attached to the housing 88. The worm gear 89 is arranged to mesh with a worm 90.

By turning the worm gears 86, 89 symmetrically the eccentric sleeve 85 and the eccentric bearing housing 88 are rotated causing the roll carrier 12 to be moved bodily towards or away from the center of the roll forging machine 10. In addition to the bodily movement of the roll carrierv 12, the ring gear 26 is caused to rotate relative to the eccentric sleeve 85 due to a pivotal movement of the bracket 83. This latter movement effectively changes the crank angle (1 thereby turning the roll curve, that is, the locus of each roll 31, so that is will bite to a greater or lesser degree as hereinbefore described with reference to FIGS. 8A and 88.

By altering the position of the bracket 83 in the frame 11 the roll curves can be altered to produce a desired result.

As the adjusting movement of each of the drive shafts 20 is circular'it is necessary that the adjustment of all four dive shafts is synchronized.

The dive shafts 20 are driven from the shafts 46 and 47 through bevel gears 48. However as the pairs of roll carriers 12 are bodily movable, the meshing pairs of bevel gears 48 have to be mounted in bearings 91, 92 which enable the gears 48 to remain in mesh whilst the roll carriers are adjusted.

FIG. 13 shows the two extreme roll curves obtainable by means of the adjustment means described with reference to FIGS. 11 and 12.

Whilst the roll carriers have been described as having five arms 30 it is to be noted that the number of arms is not limited to five and it is envisaged that each carrier could have from ring gear and the pinion can be altered as desired.

Further, if desired, backup rolls bay be mounted on each arm 30 of the respective roll carriers. With backup rolls the roll forging machine could be used with only one pair of planetary wheels to roll flats.

Various modifications can of course be made without departing from the scope of the invention since it will be obvious that numerous ways can be devised for moving the roll carriers towards and away from each other in phased relation to their rotation. For example, the carriers could be mounted in respective housings mounted in guides extending away from the pass line (conveniently at right angles to the pass line) and means would be provided for reciprocating the housings in said guides. Such means could be constituted, for example, by an eccentric drive or by a cam or by a reciprocable cam plate acting against each housing or by crank and connecting rod mechanism. Drive could be transmitted to the roll carriers by any convenient means such as by articulated drive shafts or by splined shafts, extending in the direction of movement of the housings, imparting drive to sliding gears carried in or by said housings.

l claim:

1. A roll forging machine including a frame, a pair of spaced-apart drive shafts rotatably mounted in the frame with their longitudinal axes parallel, means for rotating said shafts in synchronism in opposite directions of rotation, an eccentric on each shaft, a sleeve rotatably mounted on each eccentric, a roll carrier associated with each shaft, each carrier comprising a bush nonrotatably mounted on and concentric with each sleeve, a plurality of equal length arms projecting radially from each bush and a roll rotatably supported by each arm, said rolls being arranged with their longitudinal axes parallel to the longitudinal axes of the shafts, a pinion secured to each sleeve and a pair of internally tooth ring gears concentric one with each of the shafts, said pinions meshing with the teeth of the ring gears.

2. A roll forging machine as claimed in claim 1 comprising adjustment means for altering the path taken by the rolls of at least one roll carrier, thereby altering the distance between the paths taken by the rolls on the two carriers.

3. A roll forging machine according to claim 2 wherein the adjustment means includes a lever attached to the ring gear and means to displace the lever so that the respective ring gear is rotated relative to the drive shaft of the associated roll carri- 4. A roll forging machine according to claim 2 in which said adjustment means is arranged to displace the or each roll carrier bodily relative to a pass line of the machine.

5. A roll forging machine according to claim 4 in which said adjustment means comprises two pairs of eccentric sleeves, the sleeves of each pair are fitted one into the other, the ring gear is positioned in the inner eccentric sleeve of one pair of said sleeves, means to prevent rotation of the ring gear, the end of the drive shaft remote from the pinion is positioned in the inner eccentric sleeve of the other pair of said sleeves, and means attached to the sleeves of each pair for turning symmetrically the sleeves of each pair counter to each other.

6. A roll forging machine according to claim 4 in which said adjustment means comprise screwdowns arranged to displace the roll carriers.

7. A roll forging machine according to claim 4 in which said adjustment means comprise wedges arranged to displace the roll carriers.

8. A roll forging machine according to claim 2 in which said adjustment means is arranged both to rotate the ring gear relative to the drive shaft and to move the roll carrier bodily relative to a pass line of the machine.

9. A roll forging machine according to claim 8 in which the adjustment means comprises a first eccentric sleeve in which the ring gear is located, a lever attached at one end to the ring gear and pivotally attached to the frame at the other end, a second eccentric sleeve in which the end of the drive shaft remote from the pinion is located, and means to rotate each eccentric sleeve relative to the drive shaft.

10. A roll forging machine according to claim 1 having at 

1. A roll forging machine including a frame, a pair of spacedapart drive shafts rotatably mounted in the frame with their longitudinal axes parallel, means for rotating said shafts in synchronism in opposite directions of rotation, an eccentric on each shaft, a sleeve rotatably mounted on each eccentric, a roll carrier associated with each shaft, each carrier comprising a bush nonrotatably mounted on and concentric with each sleeve, a plurality of equal length arms projecting radially from each bush and a roll rotatably supported by each arm, said rolls being arranged with their longitudinal axes parallel to the longitudinal axes of the shafts, a pinion secured to each sleeve and a pair of internally tooth ring gears concentric one with each of the shafts, said pinions meshing with the teeth of the ring gears.
 2. A roll forging machine as claimed in claim 1 comprising adjustment means for altering the path taken by the rolls of at least one roll carrier, thereby altering the distance between the paths taken by the rolls on the two carriers.
 3. A roll forging machine according to claim 2 wherein the adjustment means includes a lever attached to the ring gear and means to displace the lever so that the respective ring gear is rotated relative to the drive shaft of the associated roll carrier.
 4. A roll forging machine according to claim 2 in which said adjustment means is arranged to displace the or each roll carrier bodily relative to a pass line of the machine.
 5. A roll forging machine according to claim 4 in which said adjustment means comprises two pairs of eccentric sleeves, the sleeves of each pair are fitted one into the other, the ring gear is positioned in the inner eccentric sleeve of one pair of said sleeves, means to prevent rotation of the ring gear, the end of the drive shaft remote from the pinion is positioned in the inner eccentric sleeve of the other pair of said sleeves, and means attached to the sleeves of each pair for turning symmetrically the sleeves of each pair counter to each other.
 6. A roll forging machine according to claim 4 in which said adjustment means comprise screwdowns arranged to displace the roll carriers.
 7. A roll forging machine according to claim 4 in which said adjustment means comprise wedges arranged to displace the roll carriers.
 8. A roll forging machine according to claim 2 in which said adjustment means is arranged both to rotate the ring gear relative to the drive shaft and to move the roll carrier bodily relative to a pass line of the machine.
 9. A roll forging machine according to claim 8 in which the adjustment means comprises a first eccentric sleeve in which the ring gear is located, a lever attached at one end to the ring gear and pivotally attached to the frame at the other end, a second eccentric sleeve in which the end of the drive shaft remote from the pinion is located, and means to rotate each eccentric sleeve relative to the drive shaft.
 10. A roll forging machine according to claim 1 having at least two pairs of opposed roll carriers arranged equidistant from a common axis.
 11. A roll forging machine according to claim 10 having two pairs of opposed roll carriers and in which at least one roll carrier of each pair is operatively coupled by means of bevel gears to at least one roll carrier of the other pair.
 12. A roll forging machine according to claim 1 in which each work roll is backed up by a larger diameter backup roll. 